1. Technical Field
The present invention relates to a motor structure and a flat type vibration motor structure using the same.
2. Description of the Related Art
In portable electronic devices such as mobile phones, game machines, personal digital assistants (PDAs), and the like, various types of vibration generation devices are mounted in portable electronic devices so as to prevent external acoustic from being damaged to others.
In particular, the vibration generation device, which is mounted in a mobile phone, has been used as a silent terminating signal generation device. Recently, as a mobile telephone is miniaturized and slimmed, a demand for a small and multi-functional vibration generation device mounted therein has increased.
The vibration generation device has used various types of vibration motors as a vibration source, wherein the vibration motor is classified into a flat type and a cylinder type according to a shape thereof and is classified into a brush type and a brushless type according to presence or absence of a brush.
Among others, the brush type flat type vibration motor can be manufactured to have a thin thickness and thus, is suitable to miniaturize a mobile phone. Therefore, the brush type flat type vibration motor has been widely used today.
Korean Patent Laid-Open Publication No. 10-2008-0033702 discloses a brush type flat type vibration motor according to the prior art.
The flat type vibration motor disclosed in the Korean Patent Laid-Open Publication No. 10-2008-0033702 is configured to include a bracket to which a lower substrate is fixed, a case covering a top portion of the bracket and partitioning an inner space, a shaft supported by the bracket, a magnet that is a stator mounted at a top edge of the bracket, and an eccentric rotor rotatably mounted at the shaft.
In this configuration, the rotor is configured to include an upper substrate having a commutator formed on a bottom surface thereof, bearings rotatably supported to the shaft, a coil and a weight body each mounted on a top surface of the upper substrate, and a molding member integrally connecting the upper substrate, the coil, and the weight body with one another.
In addition, one side of the brush is soldered to the lower substrate and the other side of the brush is soldered to the commutator, such that power from the outside is supplied to the coil.
The brush type vibration motor adopting the structure generates vibrations while the rotor rotates by electromagnetic force formed between the coil and the magnet, when the power from the outside is supplied to the coil through the lower substrate→the brush→the commutator.
Meanwhile, the flat type vibration motor according to the prior art generally has a structure in which a washer is interposed between top surfaces of the bearings and an inside of the case so that the top surfaces of the bearings do not contact the inside of the case during the rotation of the bearings.
When the washer is not interposed between the top surfaces of the bearings and the inside of the case, the bearings rotate while contacting the inside of the case. In this case, components may be worn out, noise may occur, and the like.
In order to prevent the problems, the washer is interposed between the top surfaces of the bearings and the inside of the case.
The washer generally has a disk shape. In this case, an outer diameter of the washer is larger than that of the bearing. Therefore, the top surfaces of the bearings entirely contact a bottom surface of the washer.
In the flat type vibration motor according to the prior art, the washer has a disk shape and therefore, a contact area between the washer and the bearing is bound to be widely formed. Therefore, rotation resistance is largely generated at the time of rotating the bearings and thus, power consumption may be increased and revolutions per minute (rpm) of the rotor may be reduced.